SLS

Sodium Lauryl Sulphate (SLS) is found in most shampoos and toothpaste. It is a known skin irritant and is absorbed through the skin and retained in the heart, liver and brain for long periods of time. It can cause damage to the eyes, even when absorbed through the skin. Exposure can lead to coughing, headaches, nausea and vomiting. It is an ingredient of great concern for scientists, especially when children are exposed to it. Oddly, Skin Deep only rates this ingredient a 3.

Sodium Laureth Sulphate(SLES) is a milder version of SLS with an added ether chain and is regularly found in cleansers and shampoos. It is added to thicken and give a richer consistency. It can cause skin irritation, and should be kept away from children.

Ammonium Lauryl Sulfate(ALS) is also commonly used in shampoos and cleansers. It can irritate eyes, skin and lungs but is much milder and safer than SLS. The Environmental Working Group's Skin Deep Database rates this ingredient 1-2.

Sodium Lauryl Sulphoacetate(SLSA) sounds very similar to Sodium Lauryl Sulphate, and its very easy for one to draw the conclusion that its equally bad for the body. In fact that is not the case - the two are very different. Sodium Lauryl Sulphoacetate is a very mild foaming agent and has a Hazard Ranking of 1 (low hazard) in the Skin Deep database. It is derived from coconut and palm oils and creates a rich lather that can easily be rinsed away. Its molecular size is considerably larger than SLS - it is too large to penetrate the skin, unlike the much smaller SLS molecular that does penetrate the skin and lead to skin irritations and other problems.

All of the above are anionic surfactants (or wetting agents) which are used to lower the surface tension of water.